Apparatus for manufacturing a netted structure and method for manufacturing a netted structure

Abstract

The purpose of the invention is to eliminate water-permeable sheets and thus to eliminate various bothersome works related to the water-permeable sheets. To achieve the purpose, the surfaces of the chutes 21, 22 are roughened by sandblasting. The chutes 21, 22 are made of metal such as stainless steel, for example. Processed metal surfaces are generally smooth with almost no friction. Moreover, metal has its inherent water repellency. If water is flowed on a bare metal surface, some parts do not get wet while some parts have concentrated surge water flow thereon. However, by sandblasting the surfaces of the chutes 21, 22 , adequate friction resistance is generated and inherent water repellency of metal is eliminated.

The invention claimed is: 
     
       1. A method for manufacturing a netted structure, comprising:
 a filament assembly step comprising extruding downward a molten resin as a plurality of filaments, wherein said plurality of filaments forms a filament assembly having a width and a thickness; 
 a cooling water supplying step comprising supplying cooling water downward on uniformly roughened metal surfaces of chutes for cooling said filament assembly extruded downward, said chutes being opposed to each other and being located on both sides of said filament assembly along the width direction of said filament assembly and vertical to the thickness direction of said filament assembly, and said chutes being inclined so that the distance between each said chute becomes narrower downward and toward the center of said filament assembly; 
 a loop forming step comprising receiving a first part of the filaments of said filament assembly on said roughened metal surfaces of said chutes supplied with said cooling water to form loops and make adjacent filaments within said first part of the filaments contact and entangled with each other; and 
 a dense-and-sparse portions forming step for forming surface layers having a higher apparent density and an inner layer located between said surface layers and having a lower apparent density, said dense-and-sparse portions forming step comprising:
 landing a second part of the filaments of said filament assembly directly on a water surface of a water tank; and 
 having said first part of the filaments of said filament assembly received on said roughened metal surfaces of said chutes fall down on the water surface of said water tank.